Ben Creisler
bcreisler@gmail.com
A new online paper:
W.B. Gallagher (2014)
Greensand mosasaurs of New Jersey and the Cretaceous–Paleogene
transition of marine vertebrates.
Netherlands Journal of Geosciences (advance online publication)
DOI: http://dx.doi.org/10.1017/njg.2014.30http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9419146&fulltextType=RA&fileId=S0016774614000304
Historical records of mosasaur discoveries in the Hornerstown
Formation of the Atlantic Coastal Plain of New Jersey (USA) are
reviewed in the light of recent geochemical and biostratigraphic
investigations. The highest (i.e. youngest) mosasaur remains are from
the basal Hornerstown Formation fossil assemblage, a widespread
concentration of vertebrate and invertebrate remains that coincides
with an iridium excursion and the micropalaeontological K/Pg boundary.
Most of the mosasaur specimens from this horizon are single elements,
but at least one specimen from the Hornerstown Formation, YPM 773, is
a multi-element specimen, a skull with vertebrae. This specimen is a
very large individual of Mosasaurus hoffmanni from the West Jersey
Marl Company works at Barnsboro, New Jersey. It represents the
stratigraphically highest multi-element articulated specimen in the
K/Pg section here. In and above the basal Hornerstown, the fauna is
dominated by crocodylians, lamnid sharks and chelonians. The
extinction of mosasaurs created a vacant ecological niche at the top
of the marine food web, and a trophic cascade of smaller predators
ensued. Later in the Neogene the appearance of Elvis taxa archaeocetes
such as Basilosaurus converged on mosasaur body shape.